The Paeonia emodi (P. emodi)-mediated iron oxide nanoparticles (Fe2O3 NPs) were screened for in-vitro and in-vivo antibacterial activity against the Staphylococcus aureus (S. aureus) (ATCC #: 6538) and Escherichia coli (E. coli) (ATCC #:15224). The synthesized Fe2O3 NPs were characterized via nitrogen adsorption-desorption process, X-ray diffractometer (XRD), transmission and scanning electron microscopies (TEM and SEM), energy dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopies. The SBET was found to be 94.65 m2/g with pore size of 2.99 nm, whereas the average crystallite and particles size are 23 and 27.64 nm, respectively. The 4 μg/mL is the MIC that inhibits the growth of E. coli, whereas those for S. aureus are below the detection limit (<1.76 μg/mL). The tolerance limit of the mice model was inspected by injecting different concentration of Fe2O3 NPs and bacteria suspensions. The 14 ppm suspension was the tolerated dose and the concentration above were proved lethal. The most severe infection was induced in mice with injection of 3 × 107 CFUs of both bacteria, while the inoculation of higher concentrations of bacterial suspensions resulted in the mice's death. The histopathological and hematological studies reveals that the no/negligible infection was found in the mice exposed to the simultaneous inoculation of Fe2O3 NPs (14 ppm) and bacterial suspensions (3 × 107 CFUs).
Keywords: green synthesis; hematology; histopathology; iron oxide; therapeutic activity.